The Culinary Union, caught up in a battle to organize Station Casinos workers, is threatening to sit the November election out, hurting the party's chances in Nevada.

LAS VEGAS — The largest, most powerful union in Nevada has been locked for years in a fierce and bitter battle with one of Las Vegas' most prominent families. The skirmish between workers and Station Casinos, owners of several nonunion slot palaces, is one of the biggest labor fights in the country.

Now the dispute threatens to spill over into the presidential campaign, to the detriment of President Obama, who is set to deliver an education speech Thursday in Las Vegas, and of fellow Democrats, who are grappling to gain a U.S. Senate seat to help keep Nevada's Harry Reid as majority leader.

With 54,000 members, Culinary Union Local 226 is a potent political force in one of the last bastions of labor strength. Its voter registration and turnout operations have contributed much to Democrats' success, including victories by Obama in 2008 and Reid in 2010.

Democrats are counting on another strong effort as they build their fall campaign in Nevada, one of 10 or so battlegrounds that could decide the presidential race.

But the Culinary Union's chief, expressing disappointment with Democrats and a determination to focus on other priorities, said the union and its political organizers may, in effect, sit November out.

"We're in a holding pattern because our first obligation is our contract," Secretary-Treasurer D. Taylor said in an interview at Culinary headquarters, a low-slung industrial building just off the north end of the Las Vegas Strip. "Then Station. Then politics."

The local is negotiating wages and benefits with the city's unionized casinos after foregoing a salary hike during the throes of the recession, which pushed Nevada's unemployment and foreclosure rates to the highest in the nation.

"We can't do all three things," Taylor said. "We can only do two."

Taylor may be bluffing; privately, some Democratic strategists have suggested as much. He is a famously tough bargainer and the Culinary Union is known for its pugnacity.

But Taylor's warning, delivered in a customarily bland monotone, threatens at the least to undermine Democratic unity and draw state party leaders into a contentious labor fight they have worked hard to avoid. Reid, for one, has received tens of thousands of dollars in campaign contributions from Station Casinos and its owner, the Fertitta family, giving him friends and allies on both sides of the fight.

In response, Zac Patkanas, a spokesman for the Nevada Democratic Party, said: "We are confident that our allies understand that the road to the White House and control of the U.S. Senate runs through Nevada, and are hopeful that they will be able to join us in November as they have in previous elections."

The Republicans and their presidential nominee, former Massachusetts Gov. Mitt Romney, have their own problems.

Supporters of TexasRep. Ron Paul, the former White House hopeful, have taken over the Nevada Republican Party and gone to war against the national GOP, forcing Romney to set up his own independent operation.

It is standard procedure for establishment Republicans used to working around a dysfunctional state party. But it puts the GOP at a disadvantage, starting from close to scratch against a Democratic organization, built by Reid and his team, that is one of the most disciplined and formidable in the country.

The Culinary Union has been an important cog in that machine; Local 226, with a membership that is almost half Latino, has been especially crucial in driving that key Democratic constituency to the polls.

In 2008, the union had more than 100 people working full time for three months in the presidential campaign, helping push Obama to a landslide win in Nevada. In 2010, when Reid was fighting for his political life against a tea party challenger, the union ran shuttle buses from most major casinos throughout election day, to ensure its members voted.

"They do politics very well," said Brandon Hall, who managed Reid's campaign.

The fight with Station Casinos follows a long period of prosperity and labor peace in the heavily unionized gaming industry.

Over the last 40 years, Station has grown from a single bingo parlor to more than a dozen properties, including the Red Rock Resort and posh Green Valley Ranch. The company caters to residents, leaving the high-roller and tourist trade to the glitzier Strip casinos. It has been nonunion from the start.

In 2007, Station went private in a leveraged buyout that loaded the company with debt. Walloped soon afterby the recession, the company declared bankruptcy in 2009. As the company restructured, the Culinary Union began its aggressive organizing effort.

Starting with marches and rallies, the union's tactics escalated. It began targeting Station customers and entertainers who performed at its properties, warning patrons — intimidating them, from the company's perspective — that they were wading into a rancorous labor feud.